#ifndef __PROCESS_POOL_HPP__
#define __PROCESS_POOL_HPP__

#include <iostream>
#include <cstdlib>
#include <vector>
#include <string>
#include <unistd.h>
#include <sys/wait.h>
#include "Task.hpp"

// 先描述管道
class Channel
{
public:
    Channel(int fd, pid_t id) : _wfd(fd), _subid(id)
    {
        _name = "channel-" + std::to_string(_wfd) + "-" + std::to_string(_subid);
    }

    std::string Name()
    {
        return _name;
    }

    int Fd()
    {
        return _wfd;
    }

    pid_t SubId()
    {
        return _subid;
    }

    void Send(int code)
    {
        int n = write(_wfd, &code, sizeof(code));
        (void)n;
    }

    void Close()
    {
        close(_wfd);
    }

    void Wait()
    {
        pid_t rid = waitpid(_subid, nullptr, 0);
        (void)rid;
    }

    ~Channel() {}

private:
    int _wfd;          // 文件描述符
    pid_t _subid;      // 进程id
    std::string _name; // 管道名
};

// 再组织
class ChannelManager
{
public:
    ChannelManager() : _next(0)
    {
    }

    void Insert(int wfd, pid_t subid)
    {
        _channels.emplace_back(wfd, subid);
    }

    Channel &Select()
    {
        auto &c = _channels[_next];
        _next++;
        _next %= _channels.size();
        return c;
    }

    void PrintChannel()
    {
        for (auto &channel : _channels)
        {
            std::cout << channel.Name() << std::endl;
        }
    }


    void CloseAll(){
        for (auto &channel : _channels)
        {
            channel.Close();
            //std::cout << "关闭:" << channel.Name() << std::endl;
        }
    }

    void StopSubProcess()
    {
        for (auto &channel : _channels)
        {
            channel.Close();
            std::cout << "关闭:" << channel.Name() << std::endl;
        }
    }
    
    void WaitSubProcess()
    {
        for (auto &channel : _channels)
        {
            channel.Wait();
            std::cout << "回收" << channel.Name() << std::endl;
        }
    }

    void CloseAndWait()
    {
         for(auto& channel : _channels){
            channel.Close();
            std::cout<<"关闭:"<<channel.Name()<<std::endl;
            channel.Wait();
            std::cout<<"回收"<<channel.Name() <<std::endl;
        } 
        //如何解决bug
        //法一:倒着执行关闭等待操作
        /* for (int i = _channels.size() - 1; i >= 0; i--)
        {
            _channels[i].Close();
            std::cout << "关闭:" << _channels[i].Name() << std::endl;
            _channels[i].Wait();
            std::cout << "回收" << _channels[i].Name() << std::endl;
        } */
    }

    ~ChannelManager() {}

private:
    std::vector<Channel> _channels; // 组织管道-管道数组
    int _next;
};

const int gdefaultnum = 5;

class ProcessPool
{
public:
    ProcessPool(int num) : _process_num(num)
    {
        _tm.Register(PrintLog);
        _tm.Register(DownLoad);
        _tm.Register(UpLoad);
    }
    // rfd接收文件描述符
    void Work(int rfd)
    {
        while (true)
        {
            int code = 0;
            ssize_t n = read(rfd, &code, sizeof(code)); // 从管道读取任务码
            if (n > 0)
            {
                if (n != sizeof(code))
                {
                    continue;
                }
                std::cout << "子进程[" << getpid() << "]收到一个任务码:" << code << std::endl;
                _tm.Excute(code);
            }
            else if (n == 0)
            {
                std::cout << "子进程退出" << std::endl;
                break;
            }
            else
            {
                std::cout << "读取错误" << std::endl;
                break;
            }
        }
    }

    bool Start()
    {
        for (int i = 0; i < _process_num; i++)
        {
            // 1.创建管道
            int pipefd[2] = {0};
            int n = pipe(pipefd);
            if (n < 0)
                return false;

            // 2.创建子进程
            pid_t subid = fork();
            if (subid < 0)
                return false;
            else if (subid == 0)
            {
                _cm.CloseAll();
                close(pipefd[1]);
                Work(pipefd[0]);
                close(pipefd[0]);
                exit(0);
            }
            else
            {
                // 父进程
                // 3.关闭不需要的文件描述符
                close(pipefd[0]); // 写端：pipefd[1]
                _cm.Insert(pipefd[1], subid);
            }
        }
        return true;
    }

    void Debug()
    {
        _cm.PrintChannel();
    }

    void Run()
    {
        int taskcode = _tm.Code();

        auto &c = _cm.Select();
        std::cout << "选择了一个子进程:" << c.Name() << std::endl;
        c.Send(taskcode);
        std::cout << "发送了一个任务码:" << taskcode << std::endl;
    }

    void Stop()
    {
        //_cm.StopSubProcess();
        //_cm.WaitSubProcess();
        _cm.CloseAndWait();
    }

    ~ProcessPool() {}

private:
    ChannelManager _cm; // 管道管理
    int _process_num;   // 进程数目
    TaskManager _tm;
};

#endif